When designing a network band, a service class is set in accordance with the priority order of assumed traffic. Also, in designing a network band, band allocation to each node and each service class and band control policy setting are systematically performed in accordance with the assumed input traffic amount. Related art is disclosed, for example, in Japanese Laid-open Patent Publication No. 2012-44344, and the like.
In traffic a transmission source of which is a mobile terminal, however, the mobile terminal serving as the transmission source moves. Thus, prediction of the traffic is difficult, and systematic band allocation and operation in accordance with a band control policy are difficult. More specifically, for example, there is the following problem.
FIG. 1 is a view illustrating an example network system. In a lower part of FIG. 1, a node #A, a node #B, and a node #C of nodes forming the network system are illustrated. One port of the node #A is blocked in order not to form a loop, and traffic flows in the direction from the node #A to the node #C.
Each of the node #A, the node #B, and the node #C accommodates traffic of a mobile terminal via a base station (not illustrated) or the like. Maximum transfer bands of 0.8 Gbps, 1.0 Gbps, and 2.0 Gbps are allocated to the node #A, the node #B, and the node #C, respectively, for a predetermined service class. The maximum transfer band corresponds to a peak information rate (PIR).
For example, the node #A, the node #B, and the node #C receive, as inputs, traffic of 0.8 Gbps, traffic of 0.2 Gbps, and traffic of 1.0 Gbps which join together, respectively from accommodated mobile terminals, and the output traffic amount of the node #C is 2.0 Gbps in total.
Then, when the traffic of 0.2 Gbps, which has been input to the node #B, is input to the node #A because the mobile terminal accommodated in the node #B moves, the input traffic of the node #A is 0.8 Gbps+0.2 Gbps=1.0 Gbps. The maximum transfer band of the node #A is 0.8 Gbps, and excessive traffic over the maximum transfer band of the node #A, that is, traffic of 0.2 Gbps, is discarded by the node #A.
The output traffic amount of the node #C after the mobile terminal moves, on the other hand, is 0.8 Gbps+0 Gbps+1.0 Gbps=1.8 Gbps. That is, in the example illustrated in FIG. 1, the output traffic amount of the node #C is 1.8 Gbps and, despite that the output traffic amount is less than the maximum transfer band (2.0 Gbps), a packet discard occurs in the node #A and efficiency in band use is reduced. The above-described problem might occur regardless of topology of, for example, a ring-type network, a tree-type network, a mesh-type network, and the like.